[time-nuts] OT - Tek 7L18 ROM

[Chuck Harris]

Hi Dave,

That is an issue that needs to be re-emphasized.  You can't read
the EPROMS in a 7L18 without using multiple rail supplies.  +5V
alone won't do it.

Also, the 7L18 draws too much power for any of the 4 slot scopes.
In spite of what the manual says, It is designed to operate in one
frame only, the 7603.

The biggest problem I found with mine was the tantalum electrolytic
caps on the mother board kept failing.  Also there are a pair of
shottky RF diodes being used as +/- 15V power supply isolation diodes on
the YIG oscillator that fail, killing the phase lock capabilities.
They need to be replaced with some real diodes ;-)

-Chuck Harris

Dave Baxter wrote:
> If no one else has said this.
> 
> Check the mainframe power supplies.  The 7L18 is a thirsty beast.
> 
> If anyone can back up the rom images, well done.  It's one of the
> "classic" machines internally driven by the "Original" microprocessor,
> the Intel 4004!  The Rom's will be of a similar vintage, multi rail
> supplies etc I suspect.
> 
> (I've only ever seen one other instrument that used a i4004 CPU, a
> Finnegan GC oven!)